Headlight maintenance: keep your lights in tip-top shape

Car headlights

Driving in the dark or in harsh weather can be difficult. Maintaining your headlights could help ease the stress of driving in these conditions.

Keeping your headlights in good working order is a legal requirement. And, being caught with your fog lamps on unnecessarily could lead to a fine or points on your licence.

And points on your licence could mean higher car insurance prices in future.

But you can make some simple checks to maintain your headlights and keep you safe on the road.

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Headlight laws

The Highway Code defines night-time as the hours between ‘half an hour after sunset and half an hour before sunrise’.

Within these times your headlights should be switched on, as well as during times of reduced visibility. ‘Reduced visibility’ is when you can’t see more than 100 metres ahead of you.

There are strict legal requirements to using your dipped headlights. If you fail to use them correctly the police could give you an on-the-spot fine of £50. The law says:

  • Sidelights and rear registration plate lights should be on between sunset and sunrise, except on a road lit with street lighting. These roads usually have a 30 mph speed limit.

  • You shouldn’t use any lights in a way that would dazzle or cause discomfort to other road users. This includes pedestrians, cyclists and horse riders.

  • You must also use headlights when visibility is reduced. For example, when you can’t see more than 100 metres (328 feet) in front of you.

  • You may also use your front or rear fog lights, but you must switch them off when visibility improves. 

  • In stationary queues of traffic, you should use your parking brake. You can then take your foot from the footbrake. This will deactivate the brake light and minimise glare for other road users.


How to check if your bulbs are working

Your headlights to lead the way whatever the weather and keep you and others on the road safe, so they need to function properly. If they don’t, it could endanger yourself and others.

Often the first time you know your headlights aren’t doing what they’re meant to is a warning light on the car’s dashboard.

On older cars, it’s when your headlights seem less bright that may clue you in. Sometimes a kind passing motorist may flash their lights at you at night.

Of course, flashing your lights like this isn't strictly allowed. But it’s a common habit.

The easiest way to check is to have another person stand outside and look while you operate the lights from inside.

If you’re on your own, try parking near a window or reflective surface and checking for the right reflections.


How to clean headlights

Headlight casings can get foggy, dull, yellowed and cloudy over time from oxidisation. This happens when the UV protective layer starts to degrade.

If they become too faded it might get flagged during an MOT as an advisory.

When your headlight has become too dull affects your visibility at night, it might be a time for a clean.

To determine if you need to restore and protect your headlights, first clean them with warm soapy warm and then rinse.

Run your fingers over the casing and feel if there’s any grittiness or marks in the plastic. If there are, here are a few options for you:


Find a headlight restoration service

If you don’t have time, it might be worth taking it in to a garage or a specialist that offers a headlight restoration service.

This would remove the oxidisation, polish up the lights and apply a UV protection layer. It might set you back around £50 a set depending on how much damage there is.

But with proper care, they’re likely to last longer.


Buy a headlight restoration kit

These are of varying quality and price and the methods required to get desired results. It’s worth checking out reviews to see what will best suit your needs.


Clean your headlights with the toothpaste method

This is a cheap alternative that requires a little elbow grease and time.

Buy regular toothpaste. Try to get the kind with baking soda or you can add some yourself for some abrasion.

Wash the headlights first, then apply a thick coat of paste with your fingertips. Grab your spare toothbrush and rub in small circles for between 5 and 10 minutes until the debris and grit is gone.


Use baking soda and vinegar to clean your headlights

Good old low-cost household cleaners come to the rescue of dull headlights – albeit temporarily, as you’ll need to keep it up regularly.

You can combine the two cleaners and using a microfiber cloth or toothbrush and see whether there’s any improvement after rinsing.

You might need to repeat the process. You can then add a coat of waxing compound after the plastic dries to polish the headlight.


Headlight maintenance tips

Headlights should be a part of your regular maintenance checks. Here are some things to look out for:

  • Always make sure your headlight casings are clean.

  • Check brake lights and indicators. Get a friend to look around the vehicle while you’re inside working the controls.

  • Be aware, you may not notice a blown headlight. Usually, you’ll notice a drop in brightness first, or other road users will flash their lights at you.

  • If your indicating bulb blinks faster than it should, it could mean it’s not working correctly.

  • If you're replacing bulbs, it might be worth doing so in pairs. There’s a good chance the other one won’t be far behind.

If you’re in doubt, pop to your local garage for advice.


How do I keep my headlights from getting cloudy?

The plastic on headlights is durable. But the protective film on top tends to degrade over time from sunlight, moisture and road and environmental pollutants.

It’s best to clean and maintain your headlights regularly. But if they degrade so much that it affects your visibility then you can try to restore it.

You could also buy a vinyl film to get headlight protection. Make sure you choose one that’s transparent and UV protected, and follow the manufacturer instructions carefully.

If your car is more often parked than in motion, try to park it in a sheltered area where it’s cool and dry. If you can, get a protective cover for it.


How do I know what headlight bulb I need?

To determine which headlight bulb you need, use an online bulb finder like Powerbulbs. You enter the make, model and year of your car and it gives you the fittings for each type of light for your registration.

You can find bulbs for all the positions in your vehicle including:

  • Dipped beam

  • Full/high beam

  • Side lamp.

If you can’t find it online, you can check the car manual or call up the manufacturer and ask for the fitting information.

If you feel capable it’s possible to remove the headlight, remove the bulb and check the base for details of the fitting.


Dashboard signals and their meaning 

Symbol Type of light Description
full beam
Full beam
Usually a blue coloured symbol on the dashboard.
Dipped beam
Dipped beam
This is the symbol you should see if you’re on a highway at night and encountering traffic.
front fog light
Front fog lights
These should be used when you cannot see for more than 100 metres (328 feet) in front of you. Once visibility improves, they should be switched off.
rear fog light
Rear fog lights
These should be used when you cannot see for more than 100 metres (328 feet) in front of you. Again, they should be switched off when visibility improves.
self leveling headlights
Self-levelling system
When a car behind you goes over a speed bump, the light can catch in your rear view mirror, briefly dazzling you. Self-levelling headlights stop this as they keep the lights aimed at the road.
brake light warning
Brake light warning
If there’s an issue with your brake light this symbol will usually appear.
bulb fault
Exterior light/bulb fault
This symbol will appear if there’s an issue with your exterior headlights. Either a bulb malfunction or an electrical issue.
parking lights
Parking lights
The small lights on the side of the vehicle used for parking at night.

Other dashboard warning lights can signify faults or checks that need to take place. Always keep an eye on them.  


Different types of car headlights

Xenon HID technology

If you’re driving along and notice a slightly blue tinge to another driver’s headlights, the chances are they’re HID bulbs.

HID bulbs have no filament, which can be prone to vibration. Instead, they’re filled with xenon gas and contain two electrodes (one on each end of the bulb).

When the bulb is on an electric current passes between the two electrodes and the xenon gas lights up.

This is only used during start up. Once the lamp reaches the desired temperature, other gases ensure it stays lit.

The benefit of Xenon HID bulbs is the increase in brightness. They also use much less energy to produce this light, making them an efficient option for drivers.


This stands for light-emitting diode. It uses a semiconductor diode, which glows when a current passes through it.

Again, the upside of these is that they’re bright, and they use far less energy than halogen bulbs. You also might avoid periodic bulb blows, as LEDs tend to last for more than 20 years.

The brightness of these bulbs tends to be better than halogen lamps. They’re also slightly superior to xenon-HID bulbs, as they tend not to dazzle other road users.

Always use a reputable seller if you’re interested in LED lights. Cheap LEDs can often be too bright, and cause discomfort to other road users.

You must also ensure that they’re properly aligned so they’re not shining directly in the eyes of other road users.


Headlight alignment

In the UK, headlights are dipped to the left to avoid dazzling oncoming drivers. Since 2016, the aim of the headlamp testing during an MOT changed.

The new standards emphasise correct alignment, and it’s not a quick check either.

You might not be aware that the alignment of your headlights is incorrect unless you get regular frantic flashing from annoyed oncoming motorists.

If you’re technically minded, you could try and realign the headlights yourself. Check out these guides from Champion Auto Parts and Kwik Fit for more information.